One conventional example of a combination weigher which is coupled to two packaging machines or a twin type packaging machine, is shown in FIG. 18.
FIG. 18(a) is a schematic cross-sectional view of the conventional combination weigher as viewed from a lateral side, and FIG. 18(b) is a schematic view of weighing hoppers and collecting chutes of the combination weigher as viewed from above.
The conventional combination weigher is constructed in such a manner that a dispersion feeder 1 of a conical shape is mounted to an upper portion of a center base body 9 to radially disperse objects to be weighed supplied from an external supplying device by vibration and linear feeders 2 are disposed around the dispersion feeder 1 to transfer the objects to be weighed sent from the dispersion feeder 1 into respective feeding hoppers 3 by vibration. A plurality of feeding hoppers 3 and weighing hoppers 4 are disposed below the linear feeders 2 and are arranged circularly around the center base body 9 in such a manner that each feeding hopper 3 and each weighing hopper 4 correspond to the associated one of the linear feeders 2. Each weighing hopper 4 is attached with a weight sensor 41 which measures weight of objects to be weighed inside the weighing hopper 4. Two collecting chutes 6A and 6B are disposed below the weighing hoppers 4 to gather the objects to be weighed discharged from the weighing hoppers 4 and to discharge the objects to be weighed from outlets 6a and 6b. For example, two packaging machines are disposed below the combination weigher. The objects to be weighed discharged from the outlets 6a and 6b are fed into inlets of the packaging machines.
A control unit 80 controls an operation of the entire combination weigher. The control unit 80 performs combination calculation based on measured values of the weighing hoppers 4 (values measured by the weight sensors 41) making up of a group G1 disposed above to correspond to the collecting chute 6A, and performs combination calculation based on measured values of the weighing hoppers 4 (values measured by the weight sensors 41) making up of a group G2 disposed above to correspond to the collecting chute 6B, to select in each of the groups G1 and G2, weighing hoppers 4 forming an optimal combination whose total measured value of the weighing hoppers 4 falls within an allowable range with respect to a target weight and to cause the selected weighing hoppers 4 to discharge the objects to be weighed. The objects to be weighed discharged from the weighing hoppers 4 in the group G1 are gathered by the collating chute 6A and are discharged from the outlet 6a, while the objects to be weighed discharged from the weighing hoppers 4 in the group G2 are gathered by the collecting chute 6B and are discharged from the outlet 6b.                 Patent document 1: Japanese Laid-Open Patent Application Publication No. Sho 60-161530        Patent document 2: Japanese Laid-Open Patent Application Publication No. Hei 4-204330        Patent document 3: Japanese Laid-Open Patent Application Publication No. Sho 64-12229        Patent Document 4: Japanese Examined Patent Application Publication No. Hei. 3-61895        